Abstract
Many captive Asian elephant populations are not self-sustaining, possibly due in part to obesity-related health and reproductive issues. This study investigated relationships between estimated body composition and metabolic function, inflammatory markers, ovarian activity (females only) and physical activity levels in 44 Asian elephants (n=35 females, n=9 males). Deuterium dilution was used to measure total body water from which fat mass (FM) and fat-free mass (FFM) could be derived to estimate body composition. Serum was analyzed for progestagens and estradiol (females only), deuterium, glucose, insulin and amyloid A. Physical activity was assessed by an accelerometer placed on the elephant's front leg for at least 2 days. Relative fat mass (RFM) - the amount of fat relative to body mass - was calculated to take differences in body size between elephants into consideration. Body fat percentage ranged from 2.01% to 24.59%. Male elephants were heavier (P=0.043), with more FFM (P=0.049), but not FM (P>0.999), than females. For all elephants, estimated RFM (r=0.45, P=0.004) was positively correlated with insulin. Distance walked was negatively correlated with age (r=-0.46, P=0.007). When adjusted for FFM and age (P<0.001), non-cycling females had less fat compared with cycling females, such that for every 100 kg increase in FM, the odds of cycling were 3 times higher (P<0.001). More work is needed to determine what an unhealthy amount of fat is for elephants; however, our results suggest higher adiposity may contribute to metabolic perturbations.
Original language | English |
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Article number | jeb219543 |
Number of pages | 13 |
Journal | Journal of Experimental Biology |
Volume | 224 |
Issue number | 2 |
Early online date | 26 Jan 2021 |
DOIs | |
Publication status | Published - Jan 2021 |
Bibliographical note
AcknowledgementsThe authors thank Dr Barbara Gower, Maryellen Williams, Heather Hunter and Cindy Zeng at the UAB NORC's Metabolism Core for their assistance with hormone assays and mass spectroscopy, and Dr Katie Edwards, Steve Paris and Niki Boisseau at SCBI for inflammatory and estradiol analyses. The authors thank African Lion Safari, Cincinnati Zoo & Botanical Garden, Columbus Zoo & Aquarium, Fort Worth Zoo, Little Rock Zoo, Oklahoma City Zoo, Oregon Zoo, Santa Barbara Zoo and Saint Louis Zoo for their participation in this study. Specifically, a very big thank you to the zoos' elephant keepers and elephants, who made this study possible and enjoyable. A special thank you to the Birmingham Zoo and Pat Flora and his elephant team for their continued support, help and input with method improvement.
Funding
This work was supported in part by the Smithsonian Institution, the UAB Nutrition Obesity Research Center (P30DK056336), the Diabetes Research Center (P30DK079626), the Nathan Shock Center on Aging (P30AG050886), and the National Heart, Lung, and Blood Institute (T32HL105349 to D.E.C.). Deposited in PMC for release after 12 months.
Keywords
- Body composition
- Elephantidae
- Obesity
- Reproduction
- Walking
- WALKING
- FOOD-INTAKE
- TISSUE
- INSULIN SENSITIVITY
- BODY CONDITION SCORES
- OBESITY
- LOXODONTA-AFRICANA
- FAT
- OVARIAN ACYCLICITY
- WEIGHT